5 year old male neutered GSD rescue. Been together since September 2016. Awesome dog, affectionate and typical "Velcro" temperament. However, since I have no prior history of his previous owner (he was 20 pounds underweight and heart worm positive when I got him), addressing behavioral issues has been problematic. He had no prior training or understanding of basic commands. He exhibits aggressive barking at my fiancé. The more Zelig bonds with me, the more aggressive he becomes with my fiancé. We have had 3 trainers come to the house. Only one has helped make gains in basic obedience. The barking continues  nonetheless.